在SignalR的Startup中启用UseHttpContext以便访问HttpContext。

在Startup.cs的ConfigureServices方法中添加以下代码：

services.AddSignalR() .AddJsonProtocol(options => { options.PayloadSerializerOptions.PropertyNamingPolicy = null; }) .AddHubOptions(options => { options.EnableDetailedErrors = true; }); services.AddSingleton();

并且在Configure方法中添加以下代码：

app.UseRouting(); app.UseAuthentication(); app.UseAuthorization();

app.UseEndpoints(endpoints => { endpoints.MapControllers(); endpoints.MapHub("/myhub") .RequireAuthorization(); });

在MyHub.cs中可以访问HttpContext，可以通过以下代码进行访问：

using Microsoft.AspNetCore.Authorization; using Microsoft.AspNetCore.Http; using Microsoft.AspNetCore.SignalR;

namespace My.Namespace { [Authorize] public class MyHub : Hub { private readonly IHttpContextAccessor _httpContextAccessor;

    public MyHub(IHttpContextAccessor httpContextAccessor)
    {
        _httpContextAccessor = httpContextAccessor;
    }

    public async Task SendMessage(string message)
    {
        var httpContext = _httpContextAccessor.HttpContext;
        var username = httpContext.User.Identity.Name;

        await Clients.All.SendAsync("ReceiveMessage", username, message);
    }
}

}

在上面的示例中，MyHub使用IHttpContextAccessor作为依赖注入进行构造，并在SendMessage方法中访问了HttpContext以获取用户信息。